Scottsdale, Arizona - Your doctor may monitor your blood cell counts carefully during your cancer treatment. There's a good reason you're having your blood drawn so often — low blood cell counts put you at risk of serious complications.

What's measured in a blood cell count?

If you're undergoing certain cancer treatments that could cause low blood cell counts, your doctor will likely monitor your blood cell counts regularly using a test called a complete blood count (CBC). Low blood cell counts are detected by examining a blood sample taken from a vein in your arm.

When checking your blood cell count, your doctor is looking at the numbers and types of the following:

• White blood cells. These cells help your body fight infection. A low white blood cell count (leukopenia) leaves your body more open to infection. And if an infection does develop, your body may be unable to fight it off.
• Red blood cells. Red blood cells carry oxygen throughout your body. Your red blood cells' ability to carry oxygen is measured by the amount of hemoglobin in your blood. If your level of hemoglobin is low, you're anemic and your body works much harder to supply oxygen to your tissues. This can make you feel fatigued and short of breath.
• Platelets. Platelets help your blood to clot. A low platelet count (thrombocytopenia) means your body can't stop itself from bleeding.

What causes low blood cell counts?

Cancer-related causes of low blood cell counts include:

• Chemotherapy. Certain chemotherapy drugs can damage your bone marrow — the spongy material found in your bones. Your bone marrow makes blood cells, which grow rapidly, making them very sensitive to the effects of chemotherapy. Chemotherapy kills many of the cells in your bone marrow, but the cells recover with time. Your doctor can tell you whether your specific chemotherapy treatment and dose will put you at risk of low blood cell counts.
• Radiation therapy. If you receive radiation therapy to large areas of your body and especially to the large bones that contain the most bone marrow, such as your pelvis, legs and torso, you might experience low levels of red and white blood cells.
• Cancers of the blood and bone marrow. Blood and bone marrow cancers, such as leukemia, grow in the bone marrow and don't allow normal blood cells to develop.
• Cancers that spread (metastasize). Cancer cells that break off from a tumor can spread to other parts of your body, including your bone marrow. The cancerous cells can displace other cells in your bone marrow, making it difficult for your bone marrow to produce the blood cells your body needs. This is an unusual cause of low blood cell counts.

Why is it important to monitor your blood cell counts?

Low blood cell counts can lead to serious complications that may delay your next round of treatment. Monitoring your blood cell counts allows your doctor to prevent or reduce your risk of complications.

The most serious complications of low blood cell counts include:

• Infection. With a low white blood cell count and, in particular, a low level of neutrophils (neutropenia), a type of white blood cell that fights infection, you're at higher risk of developing an infection. And if you develop an infection when you have a low white blood cell count, your body can't protect itself. Infection can lead to death in severe cases.

  Even a mild infection can delay your chemotherapy treatment, since your doctor may wait until your infection is cleared and your blood cell counts go back up before you continue. Your doctor may also recommend medication to increase your body's production of white blood cells.

• Anemia. A low red blood cell count is anemia. The most common symptoms of anemia are fatigue and shortness of breath. In some cases, fatigue becomes so severe that you must temporarily halt your cancer treatment or reduce the dose you receive.

  Anemia can be relieved with a blood transfusion or with medication to increase your body's production of red blood cells.

• Bleeding. Low numbers of platelets in your blood can cause bleeding. You might bleed excessively from a small cut or bleed spontaneously from your nose or gums. Dangerous internal bleeding can occur.

  A low platelet count can delay your treatment. You may have to wait until your platelet levels go up in order to continue with chemotherapy or to have surgery.

Your doctor may monitor your blood cell counts carefully during your cancer treatment. There's a good reason you're having your blood drawn so often — low blood cell counts put you at risk of serious complications.

What's measured in a blood cell count?

If you're undergoing certain cancer treatments that could cause low blood cell counts, your doctor will likely monitor your blood cell counts regularly using a test called a complete blood count (CBC). Low blood cell counts are detected by examining a blood sample taken from a vein in your arm.

When checking your blood cell count, your doctor is looking at the numbers and types of the following:

• White blood cells. These cells help your body fight infection. A low white blood cell count (leukopenia) leaves your body more open to infection. And if an infection does develop, your body may be unable to fight it off.
• Red blood cells. Red blood cells carry oxygen throughout your body. Your red blood cells' ability to carry oxygen is measured by the amount of hemoglobin in your blood. If your level of hemoglobin is low, you're anemic and your body works much harder to supply oxygen to your tissues. This can make you feel fatigued and short of breath.
• Platelets. Platelets help your blood to clot. A low platelet count (thrombocytopenia) means your body can't stop itself from bleeding.

What causes low blood cell counts?

Cancer-related causes of low blood cell counts include:

• Chemotherapy. Certain chemotherapy drugs can damage your bone marrow — the spongy material found in your bones. Your bone marrow makes blood cells, which grow rapidly, making them very sensitive to the effects of chemotherapy. Chemotherapy kills many of the cells in your bone marrow, but the cells recover with time. Your doctor can tell you whether your specific chemotherapy treatment and dose will put you at risk of low blood cell counts.
• Radiation therapy. If you receive radiation therapy to large areas of your body and especially to the large bones that contain the most bone marrow, such as your pelvis, legs and torso, you might experience low levels of red and white blood cells.
• Cancers of the blood and bone marrow. Blood and bone marrow cancers, such as leukemia, grow in the bone marrow and don't allow normal blood cells to develop.
• Cancers that spread (metastasize). Cancer cells that break off from a tumor can spread to other parts of your body, including your bone marrow. The cancerous cells can displace other cells in your bone marrow, making it difficult for your bone marrow to produce the blood cells your body needs. This is an unusual cause of low blood cell counts.

Why is it important to monitor your blood cell counts?

Low blood cell counts can lead to serious complications that may delay your next round of treatment. Monitoring your blood cell counts allows your doctor to prevent or reduce your risk of complications.

The most serious complications of low blood cell counts include:

• Infection. With a low white blood cell count and, in particular, a low level of neutrophils (neutropenia), a type of white blood cell that fights infection, you're at higher risk of developing an infection. And if you develop an infection when you have a low white blood cell count, your body can't protect itself. Infection can lead to death in severe cases.

  Even a mild infection can delay your chemotherapy treatment, since your doctor may wait until your infection is cleared and your blood cell counts go back up before you continue. Your doctor may also recommend medication to increase your body's production of white blood cells.

• Anemia. A low red blood cell count is anemia. The most common symptoms of anemia are fatigue and shortness of breath. In some cases, fatigue becomes so severe that you must temporarily halt your cancer treatment or reduce the dose you receive.

  Anemia can be relieved with a blood transfusion or with medication to increase your body's production of red blood cells.

• Bleeding. Low numbers of platelets in your blood can cause bleeding. You might bleed excessively from a small cut or bleed spontaneously from your nose or gums. Dangerous internal bleeding can occur.

  A low platelet count can delay your treatment. You may have to wait until your platelet levels go up in order to continue with chemotherapy or to have surgery.